Memory modules allow easy upgrades of computer systems by relatively untrained personnel. However, installation of the memory modules themselves is only a portion of the upgrade task. Often a number of system parameters must be altered as well. Upgrading often involves changing jumpers, switches, or other indicators so that the computer system correctly recognizes the newly installed memory. This additional setting of indicators is frequently the source of errors when the memory is installed by untrained personnel. Additionally, the number of parameters which need to be configured has increased as the system memory controllers attempt to use memory modules in more sophisticated ways to extract the highest performance from the memory module. Changing up to 20 parameters is not likely to be successful, even for trained personnel.
One solution to this problem is self-identification of a memory board, such as that disclosed in UK Patent Application 2,226,667A. In that application a decoder electrically coupled with memory slots and with the central processing unit receives at the time the computer system is first powered on memory size identifying information from each of the memory boards coupled with the slots. The decoder assigns system address space to each of the individual memories. UK Patent Application 2,226,666A discloses a request/response protocol, in which a processor asserts a request signal onto a system bus. A memory module corresponding to the address of the request responds with information regarding the module's characteristics. Those characteristics include whether the module can communicate in a deterministic mode, memory size, memory speed, memory type, and whether the memory is cachable to a processor.
U.S. Pat. No. 4,589,063 to Shah et al. discloses a method and apparatus for automatic configuration of a computer system. The Shah et al. system is similarly limited to self-identification of an input/output device. The patent gives examples of such input/output devices, such as graphics controllers, analog-to-digital interfaces, and computer network interface equipment.
These identification solutions do not help the user who wishes to add some RAM, less than a full board, to his computer. What is needed is self-identification for individual memory modules, rather than identification of just an entire board of devices.